The octapeptide angiotensin II is a potent pressor agent. It is formed from the decapeptide angiotensin I by the "converting enzyme" or angiotensinase. Converting enzyme has also been shown to degrade the nonapeptide bradykinin which is a vasodilator. Compounds which inhibit angiotensinase can therefore block both the formation of angiotensin II and prevent the degradation of bradykinin. By either or both of these mechanisms, inhibitors of angiotensinase are useful as antihypertensive agents both in animal models and clinically.
European Patent Application Nos. 49,505 and 49,842, Biochemical And Biophysical Research Communications, 111 (1), 166 (1983), J. Med. Chem., 25, 250 (1982), and J. Med. Chem., 24, 104 (1981) all describe 3-(mercaptomethyl)-N-lactamacetic acid derivatives which are said to be useful as antihypertensive agents by virtue of their ability to inhibit angiotensin converting enzyme.